The OBD (On Board Diagnostic) standard was initially set up by the CARB (Californian Air Resources Board) to control vehicle emissions.
The arrival of the electronic engine management computers and the associated sensors enabled the vehicles to reduce their polluting emissions. The OBD, as such, stipulates that the vehicle must, throughout its lifetime, continuously monitor the correct operation of the engine.
There are several OBD standards:
The OBD or OBDI which standardizes the connector so that it is identical to all makes and models. This protocol remains more or less distinct according to the makes.
OBDII came to the United States in 1996 to specify common protocols.
The EOBD for the European OBD with the OBDII is specific for European vehicles.
EOBD was set up in Europe at the same time as the EURO3 standard on pollutant emissions from vehicles. It specifies that emissions faults must be indicated by a warning light on the instrument panel and that codes corresponding to the detected failures must be registered by the vehicle.
Some vehicles not impacted by the Directive may, however, be compatible. It depends on the advance that the builders had on the new directive and their goodwill (activation or not of the standard).
Infographic by Wlap.org